Aastra 9143i Series Administrator's Manual page 529

Per-Line BLA
You configure BLA on a per-line basis in the configuration files using the
following parameters:
sip lineN mode
sip lineN username
sip lineN bla number
You configure BLA on a per-line basis in the Aastra Web UI using the following
fields at Advanced Settings->Line 1 thru Line 9:
• Line Mode
• Phone Number
• BLA Number
Sylantro servers and ININ servers require specific configuration methods for
per-line configurations.
For Sylantro Server
When configuring the BLA feature on a per-line basis for a Sylantro server, the
value set for the "sip lineN bla number" parameter shall be the same value set for
the "sip lineN user name" parameter for all the phones in the group. For example,
if sip lineN user name is 1010, you would configure BLA on a per-line basis for
the Sylantro server as follows:
sip line 1 mode: 3
sip line1 user name: 1010 (# for all the phones)
sip line1 bla number: 1010
41-001160-04 Rev 02, Release 2.5
Configuring Operational Features
Operational Features
5-223